“You should be able to see a slimmer waist area behind the rib cage when you look at your dog from above and also be able to feel their ribs. Cats are less likely to become overweight but we have had lots on the programme with equal success.”

It comes after research revealed pets across the UK are getting fatter.

Researchers working for the People’s Dispensary for Sick Animals produced the PAW Report last year showed 12 million pets were being fed to many fatty foods like cake, crisps and chips.

The charity claims this is fuelling a pet obesity epidemic with many animals developing life-threatening illnesses or conditions.

Avonvale’s four centres in Warwick, Southam, Wellesbourne and Kenilworth are offering free weight-management programmes individually tailored for each animal.

Baxter’s weight has fallen from a barrel-shaped 11.7kg – down to 7.9 kg since last March.

Owners David and Sandra Smith, of Frost Road, Wellesbourne, both work and live busy lives. They told how Baxter started piling on the pounds as a result of a few too many treats.

David, who works as a courier, said the couple and their two daughters began feeding him the odd crisp or chip.

“It was our fault really,” David, 44, said. “We started feeding him bits and pieces. The odd corner of toast and the odd crisp or biscuit. He became lethargic and was finding it a struggle to jump up and do the things he did before.

“Now it’s like he’s back to being a puppy again. He’s gone back to being mad and energetic again.”

Staff at the four animal centres say the dramatic weight loss is down to introducing safe, gradual changes to Baxter’s diet.

Being regularly weighed and measured saw Baxter – whose age in human years would be 49 – regain some of his old fitness from his younger years.

Post lady Sandra, also 44, said: “I’m so glad we stuck with it because Baxter is so much fitter and really enjoys his walks now.

“Kelly gave me a tip to keep it simple at home and weigh meals into little sandwich bags.

“Then all the family knew how much food to give him and his treats could be taken from this daily allowance. It really worked and he’s consistently lost weight.

“Now that he is the perfect weight for a Jack Russell we’re maintaining his new figure with lots of exercise and a maintenance plan.”